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  #1  
Old 07-30-2019, 08:26 AM
psalys psalys is offline
 
Join Date: May 2017
Location: Eugene
Posts: 26
Default Creeping bottom cowling hinge pins

Hi all,

On my newly completed RV-12iS with a Rotax 912iS engine, the bottom cowling hinge pins (the lower, longer ones) creep up out of their hinges after several hours of operation. I've tried cleaning off the lube on the pins twice, bending the pins, straightening the pins, tucking the top of the pin under the shop head of the rivet just aft of the hinge, but after a couple hours of fight, the pins will be 2 to 5 inches up out of their hinges.

A friend suggested safety wiring the pins through the cowling wall but I'd prefer not to do anything that can be seen from the outside.

Is anyone else having this problem and how have you dealt with it?

Thanks,
Patrick
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  #2  
Old 07-30-2019, 09:04 AM
Azjulian Azjulian is offline
 
Join Date: Dec 2015
Location: Scottsdale, Arizona
Posts: 156
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Have you checked the balance of your carbs as well as got a dynamic balance of your prop ? I suspect that the issue you are experiencing may be vibration induced and I would want to attack the source of vibration first.
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  #3  
Old 07-30-2019, 09:05 AM
Azjulian Azjulian is offline
 
Join Date: Dec 2015
Location: Scottsdale, Arizona
Posts: 156
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I just saw IS so presume you have a fuel injected engine ignore my carb balance point but I would check that both prop blades are at the same angle and that the prop is balanced
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  #4  
Old 07-30-2019, 09:10 AM
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Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 1,491
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I suspect you could put a slightly sharper "kink" at the bottom of the pin.
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  #5  
Old 07-30-2019, 09:39 AM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 8,280
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My suggestion is confirm prop blades are at exactly the same pitch angle (within .1 degree) and then have a dynamic prop balance done.
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RV-6A (aka "Junkyard Special ")
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  #6  
Old 07-30-2019, 11:25 AM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 2,886
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Cut a piece of hinge and cut away part of a hing barrel to make a hook for the hinge pin. See picture. This works best if the 90 degree "handle" of the hing pin is longer.
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RV-12 Flying
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  #7  
Old 07-30-2019, 12:50 PM
psalys psalys is offline
 
Join Date: May 2017
Location: Eugene
Posts: 26
Default Thanks for the suggestions

I did check the prop pitch angles and the blade track and both were good. Any suggestions on where I can get a dynamic prop balancing not too far from Eugene Oregon?
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  #8  
Old 07-31-2019, 03:29 AM
blythet blythet is offline
 
Join Date: Sep 2011
Location: selma, NC
Posts: 13
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I'll second securing the short end of the hinge pin with a short piece of hinge and nut plate. You will only have the small head of a fillister screw visible on the outside of the cowl. This modification fixed my hinge pin migration problem.
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  #9  
Old 08-01-2019, 05:20 PM
Terrybrd Terrybrd is offline
 
Join Date: Nov 2011
Location: New Smyrna Beach, FL
Posts: 39
Default hinge pin moving up

On my plane I heated up the end of the pin where you pull it and made a small loop that closes on itself and then used a small piece of safety wire with one end attached somewhere close and run the other end through your loop and just put a small bend in the safety wire after the loop and mine never moved after that.
just straighten the wire and pull out and the pin just pulls out as usual.


Terry
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  #10  
Old 08-01-2019, 05:39 PM
Cammie Patch Cammie Patch is offline
 
Join Date: Oct 2018
Location: Boise, ID
Posts: 20
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I drilled a small hole in a flange on the firewall angles and put a tie wrap through the hole and over the end of the pin.
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